1. Field of the Invention
The present invention relates to an optical pickup apparatus for an optical disk drive, more particularly, to an optical pickup apparatus for an optical disk drive for recording or reproducing data while floating by air bearing generated between the optical pickup apparatus and an optical disk.
2. Prior Art
Generally, an optical disk player is a device for recording or reproducing data on or from an optical disk, such as a CD, a CD-ROM, a DVD, or a DVD-ROM, and includes an optical pickup apparatus. The optical pickup apparatus records or reproduces the data by projecting a light on a recording surface of the optical disk.
An exemplary optical pickup apparatus is disclosed in U.S. Pat. No. 5,144,607. The optical pickup apparatus of the U.S. Pat. No. 5,144,607 includes an object lens for focusing a light on the optical disk, a bobbin for supporting the object lens, a wire spring for movably supporting the bobbin to/from a base, and a driving unit moving the bobbin. Moreover, the driving unit includes focusing coil wound around the bobbin for driving the bobbin in a focusing direction of the light, tracking coils for driving the bobbin in a tracking direction, which is perpendicular to the focusing direction, and magnets disposed corresponding to the focusing and tracking coils.
In the above construction, the position of an optical head including the object lens is determined according to the driving of the respective coils. That is, the position of the optical head is adjusted by moving the optical head toward or away from the optical disk using an electromagnetic force, which is generated when the electric current is supplied to the focusing coil. Also, the position of the optical head is adjusted in the tracking direction crossing the focusing direction when the electric current is supplied to the tracking coils. Here, a focusing error may be generated when the light projected from a light source is incident on the object lens through a light path and is focused on the surface of the optical disk. However, by adjusting the positions of the optical head minutely, the focusing error can be minimized.
However, conventional optical pickup apparatuses such as the apparatus of the U.S. Pat. No. 5,144,607, have high power consumption because these apparatuses require continuous electric current supply to the focusing coil for minute adjustment of the position of the optical head. Moreover, because the adjustable distance between the optical disk and the lens by the electromagnetic force is limited to about 1 mm, these conventional optical pickup apparatuses are difficult to apply to a high-density near field drive that requires a distance of less than tens of nm.
An optical recording or reproducing apparatus using an air bearing slider is disclosed in U.S. Pat. No. 5,150,338. The optical recording or reproducing apparatus of the U.S. Pat. No. 5,150,338 includes an object lens mounted on an air bearing slider, and the air bearing slider is connected to an actuator of a rotary type or a linear type. While driving the actuator, if an object lens of the optical recording or reproducing apparatus is positioned on a desired track of a recording surface of a magneto-optical memory disk, the air bearing slider floats over the optical disk and then maintains a minute focusing distance to/from the optical disk by an air bearing which is generated from the structure and weight of the slider and high speed rotation of the disk.
The actuator of the optical pickup apparatus of the U.S. Pat. No. 5,150,338 requires a servo control in the optical pickup to position the object lens on the desired track of the disk, and requires a high servo bandwidth due to a removable characteristic of the disk. However, when the air bearing slider is supported by a suspension, the available servo bandwidth is limited due to a limited frequency of the suspension.